%% You should probably cite draft-billon-expires-09 instead of this revision.
@techreport{billon-expires-03,
    number =    {draft-billon-expires-03},
    type =      {Internet-Draft},
    institution =   {Internet Engineering Task Force},
    publisher = {Internet Engineering Task Force},
    note =      {Work in Progress},
    url =       {https://datatracker.ietf.org/doc/draft-billon-expires/03/},
    author =    {Benjamin BILLON and John R. Levine},
    title =     {{Updated Use of the Expires Message Header Field}},
    pagetotal = 5,
    year =      2022,
    month =     apr,
    day =       14,
    abstract =  {This document allows broader use of the Expires message header field for SMTP. Senders can then indicate when a message sent becomes valueless and can safely be deleted, while recipients would use the information to delete these valueless messages.},
}